Field of the Invention
The present invention relates to a surface treatment process that is effective for preventing pattern collapse during formation of a fine pattern having a high aspect ratio, and relates to a surface treatment liquid that is used in the surface treatment process.
Related Art
In the production of semiconductor devices or other devices, lithography technology is used for treatment of substrates, such as etching. In this lithography technology, a photosensitive resin layer made of a photosensitive resin composition is formed on a substrate and is then selectively irradiated with and exposed to active radiation for development. Thereafter, the photosensitive resin layer is selectively removed by dissolution to form a resin pattern on the substrate. Subsequently, etching is performed using the resin pattern as a mask to form an etched pattern, such as a silicon pattern, on the substrate.
In recent years, the integration and miniaturization of semiconductor devices have been enhanced, and the refinement and increment of the aspect ratio in etched patterns have also advanced. However, such progress has simultaneously caused a problem so-called pattern collapse. Pattern collapse occurs when a large number of patterns are formed in parallel on a substrate and is a phenomenon in which adjacent patterns approach each other so as to lean on each other and, in some cases, causing breakage at the basal part or detaching of the pattern. Such pattern collapse may be an obstacle for production of a desired product, leading to a reduction in yield or reliability of the product.
It is known that the pattern collapse occurs during cleaning treatment after the formation of patterns by the surface tension of a cleaning liquid when the cleaning liquid is dried. In other words, when the cleaning liquid is removed during a drying procedure, stress based on the surface tension of the cleaning liquid is applied between the patterns to cause pattern collapse.
Accordingly, many approaches have been attempted for preventing pattern collapse by adding substances that decrease surface tension to cleaning liquids. For example, a cleaning liquid containing isopropyl alcohol and a cleaning liquid containing a fluorine-based surfactant have been proposed (e.g., Patent Documents 1 and 2). Alternatively, a surface treatment liquid containing a silylating agent and a solvent has been proposed (e.g., Patent Document 3).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H06-163391
Patent Document 2: Japanese Unexamined Patent Application, Publication No. H07-142349
Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2010-129932